Trim List if List GVK is provided

Signed-off-by: Tamal Saha <tamal@appscode.com>

pkg/cache/informer_cache.go

@@ -96,11 +96,11 @@ func (ip *informerCache) objectTypeForListObject(list client.ObjectList) (*schem
 		return nil, nil, err
 	}
 
-	if !strings.HasSuffix(gvk.Kind, "List") {
-		return nil, nil, fmt.Errorf("non-list type %T (kind %q) passed as output", list, gvk)
-	}
 	// we need the non-list GVK, so chop off the "List" from the end of the kind
-	gvk.Kind = gvk.Kind[:len(gvk.Kind)-4]
+	if strings.HasSuffix(gvk.Kind, "List") && apimeta.IsListType(list) {
+		gvk.Kind = gvk.Kind[:len(gvk.Kind)-4]
+	}
+
 	_, isUnstructured := list.(*unstructured.UnstructuredList)
 	var cacheTypeObj runtime.Object
 	if isUnstructured {